fix(runs): RunRequest builder

Author: aallam

openai-core/src/commonMain/kotlin/com.aallam.openai.api/run/RunRequest.kt

@@ -84,7 +84,7 @@ public class RunRequestBuilder {
      * Appends additional instructions at the end of the instructions for the run.
      * This is useful for modifying the behavior on a per-run basis without overriding other instructions.
      */
-    public var additionalInstructions: String? = null,
+    public var additionalInstructions: String? = null
 
     /**
      * Override the tools the assistant can use for this run.